I want to build a 2.x engine

[FuJi K]

With Subaru engines being like legos, you can assemble an engine with a size of anywhere from a 2.0L to like say a 2.7L. Of course you have to have the know how and some experience in engine building to understand what you are doing. Which ever combination you choose will determine how your power-band will look like with your whole setup. Here we will look at how you can swap parts around to make a few combination's and also some other crazy ideas if you have some money to burn.

First lets determine what your engine management is going to be because it will determine what heads you can run. If you have a 2002+WRX/2004+STi/FXT/Baja XT/Legacy&Outback 2005+ this will make it easy for you since your factory ECU is supported from AccessPort by Cobb Tuning, ECUTec, OpenSource, as well as a full replacement after market ECU such as Hydra, AEM, and even Motec. If you own an older engine swap that is in the Impreza GC8 era, Legacy BF/BG, Forester SF, you may need to find alternatives like chipping the ECU, piggyback as well as full aftermarket ECU swap to Apexi PowerFC, Link, Hydra, or Motec just to name a few.

Knowing what engine setup you have plays a big factor in fitting those heads onto the block because of bore size vs combustion chamber size. It can alter compression ratio as well as detonation problems and air flow into and out of the engine. The EJ205 combustion chamber matches the 92mm bore of the EJ20. The EJ257 combustion chamber matches the 99.5mm bore of the EJ25. The EJ20K/EJ25D heads have a clover combustion chamber and was made for the EJ20 bore. However the USDM 1996 EJ25D specifically was made with a wider combustion camber to fit the EJ25 bore. You do not ever want to put like a EJ257 head onto a smaller bore than what it was made for.

What turbo size are you planning to go with and what fuel? Knowing what turbo you are going with determines how you build your engine. The fuel type allows you to better make use of larger turbos and even small turbos. The turbo produces the power-band and you can broaden it by using the right matching parts to work with the engine operation speeds. Smaller turbos focus more in the lower mid range power band. Medium turbos focus more mid range. Big turbos are more in the upper engine speeds. Build your heads to suit that power-band so you make the most out of your whole setup. The engine combination you choose alters the power-band where it's more focus.

Let's try to understand the EJ-phase1 and phase2 blocks. Phase1 EJ-blocks are the first blocks Subaru made and for US models started in 1990-1998. There are less bolts on the bell housing holding the engine to the transmission. You have your top two bolts, which are longer with the driver side going through the starter, and the passenger side going through the transmission and which ever bracket there is for NA engines. Then you just have the studs that come out at the bottom of the block. Phase2 blocks start in 1999+ and use six bolts holding the transmission onto the engine with the two studs at the bottom.

The thrust bearing on the crankshaft is located on main bearing #3 on the phase1 block, which is the middle of the five mains. This thrust bearing as you may know keeps the crank from moving forward and backwards when you disengage the clutch. Other differences are the exterior casting of the block and varies in casting bracing and ribs as it progress through the years. Phase2 has its thrust bearing on #5 main bearing, which is the last main bearing on the crankshaft. However they both use the same #3 main crank journal to feed connecting rods #2 and #3 where as connecting rods #1 and #4 get their own individual oil feed.

The internals vary in journal sizes and strokes for both phases depending on the engine size. Phase1 EJ20 and EJ22 uses the same crankshaft dimensions. They both run a 75mm stroke and have the same rod journals of 52mm. The phase1 EJ25 however uses a 79mm stroke, but with a 48mm rod journal to compensate for the longer stroke. Phase2 EJ-series crankshafts all use the same 52mm rod journals but vary in strokes of 75mm and 79mm. Overseas Subaru has crankshafts with much smaller strokes such as a 65.8mm on the EJ15/EJ16. The rod lengths are the same length for phase1/2 EJ20 and EJ22, as well as the phase2 EJ255/EJ257 and '05+ EJ25 NA models. Rod length for the phase1 EJ25 is different from the rest of the EJ-series for US models.

Now lets get to the fun part. Now which ever crank and bore size you choose will determine how your power-band will look like with your whole setup. The base EJ20 tends to be a higher RPM engine. The EJ22 gives you some more mid range. The EJ25 gives you more mid range and low end grunt.

Knowing what phase block you have, you can swap cranks around and even use connecting rods that may have not been made for your engine to begin with. Now you can only use the crankshaft with the correct thrust bearing on which ever phase block you have. To alter this you will have to have the block's main bearing machined to fit the thrust bearing in which the crank calls for. Usually this applies to phase1 blocks wanting to use phase2 cranks so #5 main gets machined on the block to fit the new thrust bearing and #3 main gets notched to fit the tab of the phase2 bearings. This is the best way to go about it to be able to use the different thrust bearing location cranks.

Now that you have that done you can choose your rods. All the turbo rods now are made the same because they all share the same rod length. If you have a EJ25 phase1, your rod will be different because of the 48mm rod journal. There are few companies that still make the 48mm rod journal connecting rod but will cost you some to get customs ones made if you need it. Pauter may still have these rods if you are wondering.

Now the pistons are what you have to get now. The piston goes with the block you have. EJ20 means you have to get the piston to fit that bore. Same goes for EJ22 and EJ25. Now depending which crank you choose, you may have to change the wrist pin location. You run a EJ20/EJ22 with the OEM 75mm crank and you do not have to worry about wrist pin location. However when you change that crank to a 79mm crank, the added 4mm pushes the piston up and extra 2mm up top and pulls it down and extra 2mm at the bottom. To counter this you have to raise the wrist pin higher, thus dropping your compression height dimension by 2mm. The same would be for a EJ25 engine using a 75mm crank having to lower the wrist pin, thus adding 2mm more to the compression height dimension. You can also counter this by using a connecting rod that is longer by 2mm to make up the difference and keep the wrist pin at its original location. NOTE: Phase1 pistons tend to come out of the block and over the deck. You may want to use phase2 piston compression height dimensions.

The head gasket now is what we are wondering. You want to use the HG to is the same thickness as stock. It will keep the overall width from cam gear to cam gear. This keeps the timing within the correct range. When you change the thickness this changes the timing degree. You do not want to use the thickness of the head gasket to alter compression ratio. You should change compression ratio with pistons. The coolant passages may be altered or covered up a little depending what block you are using. You can have them modded or have the one made for you. Cometic may be able to help you with that.

Now that you have the major part finished, you can add on top of that different compression ratios by altering the pistons either by off the shelf pistons or custom. You can also set the specs to make the car produce more off boost grunt. You can add bigger cams if you built the engine for more RPMs. Now go and build that engine!

Other changes you can make are by altering the short block much more. You can add sleeves to it. You can change to a much larger or smaller stroke. You can add rod length to it. You can change piston dish design. You can increase bore size. All of this will alter the engine's power-band. How about a 65.8mm crank with +6mm rods on a 2.0L bore NA build with ported heads and long duration cams? Maybe 14,000rpms? Or how about a built 79mm stroked EJ22 with +2mm rods and 9000rpms boosted? Or say a simple sleeved EJ25 79mm with +2mm rods and high boost with 9000rpms? Maybe an EJ20 with +4mm rods and 10,000rpms might be fun with the right turbo? Fun comes with a wide power-band.




Please read the sticky to get yourself familiar with the engine parts.
http://forums.nasioc.com/forums/show....php?t=1431376






Please add more to this if you'd like and your experiences. I hope this helps. We're late in the game of performance. Honda and Mitsubishi have loads of info.

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[FuJi K]

Phase 1 Engines
-75mm stroke with 52mm rod journal
-79mm stroke with 48mm rod journal
-130.5mm rod length (exception EJ25 is 131.25mm)
-thrust bearing is main bearing #3
-2 bolts at the very top and 2 studs at the bottom

Phase 2 Engines
-75mm stroke with 52mm rod journal
-79mm stroke with 52mm rod journal
-130.5mm rod length & '05+ EJ25 NA(exception '99-'04 EJ25 NA 131.6mm)
-thrust bearing is main bearing #5
-6 bolts top to bottom with 2 studs at the bottom


BORE x STROKE
EJ18 - bore/stroke
- 87.9mm x 75mm

EJ20 - bore/stroke
- 92mm x 75mm

EJ22 - bore/stroke
- 96.9mm x 75mm

EJ25 - bore/stroke
- 99.5mm x 79mm


COMBUSTION CHAMBER CC
S20/S20V/W20: 49cc
D25: 50cc
B25/V25B/W25: 57cc


Combustion Chambers of Various Heads
B25/V25B/W25 - approx 99.5mm across



D25 - approx 97mm across



S20/S20V/RH C/H25/W20 - approx 92mm across




It would be easier if you swapped out your rods to WRX/STi spec to make other parts easier to get.


Reference to other Subaru EJ-series engines and their specifications:
http://en.wikipedia.org/wiki/Subaru_EJ_engine

[FuJi K]

Thrust #5 conversion
Here you can see where the factory machining was for the original #3 thrust bearing.




Here is where it has been cut to fit #5 thrust bearing and a phase2 EJ205 crank fitted with Eagle rods.




Here is an EJ257 with the OEM thrust location #5




Combustion Chamber VS Bore Size
Here is a 2.0L EJ205 S20 combustion chamber on a 2.2L 97mm bore.



Here is the 2.0L EJ205 S20 combustion chamber on a 2.5L 99.5mm bore.



Here is a modded 2.0L EJ205 S20 combustion chamber to a 97mm width on a 2.2L 97mm bore.



Here is a modded 2.0L EJ205 S20 combustion chamber to a 97mm width on a 2.5L 99.5mm bore.



Here is a stock 2.5L EJ255/EJ257 B25 combustion chamber to a 97mm bore.

[FuJi K]

2.3L Destroke EJ25
-EJ257 connecting rod
-EJ205 crankshaft; 75mm stroke
-Wiseco OTS 8.9:1CR piston for EJ257
-Compression height for EJ257
NOTE: You can see the piston doesn't come all the way to the top of the deck. This is due to the smaller 75mm stroke. It falls 2mm shorter up top and 2mm bottom. This adds up to the 4mm difference in the OEM stroke of 79mm vs the new stroke of 75mm. Pistons would need to be made with an additional 2mm added to the compression height to make up the difference. You can also use connecting rods that are +2mm longer than factory to make up the difference. Take note that even if you're using a longer rod, the compression ratio will be LESS than advertised for that piston you're using. This would be the same for a piston that retains the same dish cc but only compression height changed. Reason being is because the stroke is less.






2.35 Stroked 2.2L (applies for 2.0L as well)
-EJ257 connecting rod
-EJ257 crankshaft; 79mm stroke
-Custom CP Piston 9.0:1CR piston for EJ22T with EJ205 compression height
-Compression height for EJ205
NOTE: You can see the piston comes all the way out the top of the deck. This is due to the larger 79mm stroke. It extends 2mm taller up top and 2mm bottom. This results in the 4mm difference in the OEM stroke of 75mm vs the new stroke of 79mm. Pistons would need to be made with -2mm taken away from the original compression height to make up the difference. You can use connecting rods that are -2mm shorter than factory to make up the difference, but that would change your rod ratio. Take note that even if you're using a shorter rod, the compression ratio will be MORE than advertised for that piston you're using. This would be the same for a piston that retains the same dish cc but only compression height changed. Reason being is because the stroke is more.





However take note that if you have a longer skirt, you might want to make sure it clears the lower case main suppports. These skirts are wide thus cam in contact with the lower case of the block. If they where short skirts they would not come in contact. If the skirts where as WIDE and just the center part of the skirt was extended, it would clear the lower case main supports. This picture shows a combination of EJ257 crank, EJ257 connecting rod, and custom CP piston with longer and wide skirts with EJ205 compression height.



CP piston skirt compared to the EJ22T OEM piston skirt

[Homemade WRX]

you may want to clarify that the 48mm rod journal doesn't have anything to do with stroke. Also I didn't see where the phase 2 NA EJ25 rods were a different length as well (131.6mm) and are different from the phase 1 as well (131.25mm IIRC).

Still reading through but it's late.

Looks good but it may be easier to read if you list things i.e.

Phase 1 motors
-52mm rod journal (exception EJ25 is 48mm)
-130.5mm rod length (exception EJ25 is 131.25mm)
-Thrust bearing is main bearing #3

Phase 2 motor
-52mm rod journals
-130.5mm rod length (exception EJ25 NA and 08+)
-thrust bearing is main bearing #5

something like that. It makes for less hunting and pecking through sentences/paragraphs. I have a feeling it'll make for fewer questions. Perhaps a simple right up explaining how to measure up total reciprocating length in relation to deck height, since that confuses MANY people. I think that alone will greatly reduce questions from peope in regards to stroke, rod length and compression height. Then they'll also grasp quench height, headgasket thickness and can bounce right into compression ratio. An engine 101 if you will. Easiest way to show it is showing the total deck height and showing how the different part measurements add together. I see you are getting into it. I'm just thinking of an easy way to show it.

[25rsti]

Awesome stuff. Thanks for the time spent on this Fuji. Sticky for sure.

[Homemade WRX]

Might want to add the behllhousing bolt pattern differences too as a heads up for phase 1 and phase 2 differences.

did you want to touch on various bore sizes and strokes?

To clear up much confusion on how stroke, rod length and compression height factor up with deck height. If I recall correctly, deck height is 201 mm from the factory. Once a deck is machined, this obviously changes.

crank radius + rod length + compression height = X mm
75mm stroke = 37.5mm radius
37.5 + 130.5 +32.7 mm = 200.7 mm

79mm stroked EJ18/20/22 = 39.5mm crank radius
39.5mm + 130.5mm + 30.7mm = 200.7mm

You can see the compression height of the piston OR the rod length make up the difference from the change in stroke.

[Ferraz]

Very nice work, guys!! Subscribed!

[berge56]

subscribed

[hustleshark206]

Looks good Fuji! Maybe some pics would help?

[FuJi K]

I'll add some pictures soon. Hands a little full at the moment with heads and blocks... lol

[aesthetect]

good man, fuji

[kakarot09]

Nice, a bunch of the info from a ton of research I've done all in one thread lol. Now if you could put a bunch of head measurements like this too Maybe take your head thread and combine it with this a little bit. Like the post where you have phase one and two measurements for the block you could add the casting of the head and measurements/descriptions for them. Then you can see what works together and what doesn't. Also what year and car the head casting designations correspond to is helpful. Good job so far though

[FuJi K]

I'll add more pictures once the engine comes back from the machine shop. I don't want to pull out my oily EJ22T block... I have I'll be putting together here shortly with 90% the same how my personal engine was spec'd out.

[FuJi K]

2.2L added. More pics to come.

[jetski247]

great job, now im thinking of a de stroke 257 but not sure if its any better since i want quick spool, why de-stroke? just rpm? can it just rap out faster? upper rpm power?

turbo scoobies are new to me but i'm learning. i would think small bore/long stroke would be a very reliable setup? small piston=strong, long stroke=torque?

a detailed scoobie engine wiki.........i like

[john 1badSTI]

Nice job fuji and nice add on Micah,really nice hd pics there fuji and a destroked 2.5 does sound like a nice set-up with the +2mm rods.IIRC that was the motor combo some of the guys going fast in pr were using.

[NW2TONE]

Originally Posted by john 1badSTI

Nice job fuji and nice add on Micah,really nice hd pics there fuji and a destroked 2.5 does sound like a nice set-up with the +2mm rods.IIRC that was the motor combo some of the guys going fast in pr were using.

ohh yeah.. we have 7 sleeved destroked 2.5s getting going at mps right now. 6 blocks heading out this week for sleeves
I cant wait to get mine in my forester

Def tons of good info in here to help people decide what will best suite thier needs.

[Homemade WRX]

Originally Posted by jetski247

great job, now im thinking of a de stroke 257 but not sure if its any better since i want quick spool, why de-stroke? just rpm? can it just rap out faster? upper rpm power?

ask in the official long rod thread, so that we don't hi-jack this thread but put simply, yes

[john 1badSTI]

wow how fast does Dan Benson turn them around for Dom? thats just crazy 6 blocks at once.

[Homemade WRX]

Maxwell Power kind of handles Dan Benson orders as they have some sort of deal sorted out. Helps Dan not have to answer the phone as much and Maxwell coordinates the sales...or something along those lines.

[FuJi K]

Combustion chamber and bore pics added. The modded '97mm EJ205 heads is the same width as the D25 head.

[john 1badSTI]

So your saying that if you want a block sleeved and such its best to go thru Dom to coordinate everything if you want Benson to do the work.

[Homemade WRX]

Yes, if you want Benson to do the sleeving, it is easiest and probably cheapest to send through Maxwell. They're in cahoots with Benson

[ogboot]

Fuji I love you. You basically took the info I've been poring over in the built forum and put it together in a nice easy to read guide. I'm slowly compiling knowledge to build a motor with my spare heads. Thank you so much. /subscribed